Pneumatic action for pianos



W. G. BETZ. PNEUMATIC ACTION FOR PIANOS.

APPLICATION FILED JUNE 1, I916.

Patented Mar. 30, 1920.

[EL/5277527. DMZ/25277515572.

2' 2755555." WQWKQLQQK UNITED STATES PATENT WILLIAM G. BETZ, OF BUFFALO,NEW YORK, ASSIGNOR TO STRA'UBE PIANO COMPANY, OF HAMMOND, INDIANA, ACORPORATION OF INDIANA.

PNEUMATIC ACTION FOR PIANOS.

Specification of Letters Patent.

Original application filed May 8, 1914, Serial No. 837,130. Divided andthis application filed June 1, 1916.

- Serial No. 101,145.

lily invention relates to pneumatic actions for pianos, the presentapplication which 18 i a division of my application filed May 8th, erialNo. 837,130, Patent No. 1197596, be directed more particularly toactionoperating mechanism. One of the principal objects 01': the presentinvention is to provide an improved construction for hanging or.supporting, and regulating, action levers whereby such levers andsupporting arms are pr rably individually removable. In pneuznadcactions a bellows for each hamlner action is ordinarily provided andconnecting links or levers are used for connectin the bellows and hammeractions. It is of advantage to be able to regulate the stroke of thebellows or connected levers and by my red construction I support theconnecting link or lever by individually removable arms which also carryadjusting means for regulating thestroke of the bellows and connectedlevers. o

I will now refer to the accompanying drawing for a better understandingof my invention in which like reference characters indicate like partsand in which- Figure 1 is a sectional view illustrating he controlmechanism of one key;

Fig. 2 is a face view of one valve mechanism with the cover of the airchamber removed;

- Fig. 3 is a side elevation of a valve lever;

Fig. 4: is a left side view of Fig. 3;

Fig. 5 is a detail view of a combined. valve lever support and valveseat; and

Fig. 6 is a sectional view through the center of Fig. 5; and

Fig. '7 is a plan view of a portion of Fi 1 showing the preferred methodof independently mounting'the action levers and lever-supporting arms.

In the preferred embodiment of my invention as illustrated, I provide aso-called air chest or chamber A, comprising preferably verticallydisposed facing walls 1 and having spacers as 3, 4, the cap or wall 2Pianos, of which the following being attached by screws 5 so that it maybe readily removed. This chamber A is, of course, of such length andwidth as to suitably take care of the desired number of valvemechanisms, as will be readily understood.-

A single valve mechanism B is shown comprising a plate 6 having acentrally disposed air port 7 formed so as to provide a valve seat 8,and above said port a pair of inwardly projecting ears 9 are formed,having concave formations 10 for supporting the valve lever shaft. Plate6 is secured to the inner surface of the wall 1 preferably byscrews 11,the valve seat 8 projecting into a chamber 12 having a valve seat 13,said chamber 12 having an atmosphere duct 1% and bellows duct 15.

A valve lever 27 i is provided, having a pointed shaft 28, which issprung between the resilient arms 9 and held between the concavedportion 10 in such a manner that the depending lever 27 is free toreciprocate without any lateral movement, thus doing away with guides,such as have been previously used. 7

At thecfree end of lever 27, a valve gate 29 is adjustably. attached bymeans of a screw 30, said valve vgate having facings preferably ofleather, which act upon valve seats 8 and '18.

At a, point preferably intermediate of the pivoted end of lever 27 andthe valve support 30, a buffer 31 i adjustably secured,

said buffer cooperating with a diaphragm 32, which is preferably ofrubber or leather, and suitably fastened over the diaphragm actuatingchamber 33. Chamber 33 is preferably round, and a duct 34: leadstherefrom to a tube 35 extending to its tracker bar port 36. Aconnecting duct 37 leads from the main air chamber A to each duct 34:,there being a cap 38 provided with a small open ing inserted in eachduct 37 to allow only a small flow of air. A tube from chamber A is alsoconnected to the vacuum pump to create a vacuum in chamber .A in awellknown manner.

It will, of course, be understood that in using my invention, the airchest is made wider than shown, and the associated bellows and valvemechanisms are staggered in accordance with well known practice.

ably fastened to the wall 1 in connection with duct 15 and is connectedto a hammer action lever 16 by means of a connecting rod 17, which ispivotally attached at its upper end and held to the bellows extension 18by a pair of ball faced nuts 19.

Each action lever 16 is pivotally secured to an individual arm 20, whichis detachably secured to a rail or bar 21 preferably by means of screws22, said rail being suitably supported, preferably by screws 23. Anoverhanging portion 20 of arm 20 carries an adjustable stop 24L, wherebythe upward travel of action of lever 16 is determined. An adjustablebuffer screw 26 is also carried by lever 16, which lever acts upon theaction mechanism D, as will be readily understood.

Each action lever 16 and its supporting arm being individual units itwill be apparent that they may be readily detached or replaced withoutdisturbing others.

In the operation of the action, a vacuum is created in the air chamber Aby suitable means, and with the music sheet covering the duct 36 avacuum is also created induct 34. Thus the atmospheric pressure againstvalve 29 tends to hold valve lever 27' in its normal or inoperativeposition, and therefore the bellows C is maintained open. Upon openingtracker port 36, duct 34 tends to come up to atmospheric pressure,resulting in a pressure against diaphragm 32 by the pressure in chamber33. Buffer 31 therefore acts upon lever 27, which causes valve gate 29to leave its normal or air chamber port seat and engage the atmosphereduct seat 13, whereby the bellows chamber is connected to the chamber Aby duct 15. A vacuum is thus created in the bellows chamber, allowingthe atmospheric pressure to close the bellows, whereby the arm 18 israised and through connecting rod 17 and lever 16 the hammer actionmechanism D is actuated.

Upon closure of port again, duct and chamber 33 being connected tochamber A again have the pressure therein reduced so that theatmospheric pressure acting upon valve 29 through duct 1a, forces thevalve gate 29 against its seat 3 and thus the bellows chamber beingconnected to atmosphere through ducts 15, 14, again opens and restoresthe action mechanism D.

Although in illustrating my invention 1 have chosen a preferred form, itis to be understood that it may be applied to other arrangements;neither do i desire to be limited to the construction shown as changesand modifications will readily occur to those skilled in the art, and Iaim to cover all those changes and modifications as come strumentscomprising a horizontal rail,

action-operating bellows below the rail and extending transverselythereof, a horizontally-disposed action-lever positioned above eachbellows lying longitudinally thereof and operatively connected thereto,independently-removable lever-supporting arms secured to said rail eachpivotally supporting one of said action-levers, an extending portionindividual to each of said arms overhanging the corresponding lever, andan adjustable stop carried by each of said ex-- tending portions forcontrolling the travel of the corresponding arm.

3. A pneumatic action for musical instruments comprising a horizontalrail, leversupporting arms independently and detachably secured at oneend to the rail and projecting laterally therefrom, an actionlever foreach arm having one end pivotally attached to an intermediate portion ofthe arm whereby an extending portion of the arm is positioned adjacentan intermediate portion of the lever, and adjusting means for regulatingeach lever carried by the extending portion of the associated arm.

A pneumatic action for musical instruments comprising a supporting rail,straight rectangular elongated lever supporting arms independently anddetachably secured at one end to a horizontal side of the rail andprojecting laterally therefrom, an actionlever for each arm having oneend pivotally attached to an intermediate portion of the arm whereby thefree extending portion of the arm is positioned adjacent an intermediateportion of the lever, and adjusting means for regulating each levercarried by the extending portion of the associated arm.

Signed by me at Chicago, county of Cook and State of Illinois, in thepresence of two witnesses.

WILLIAM G. BETZ. Witnesses:

GEORGE E. MUELLER, JENNIE B. STALEY.

